Three senior directors of Tesco were accused in court yesterday of abusing their positions on the board of garden centre chain Dobbies in an attempt to oust billionaire financier and minority shareholder Sir Tom Hunter from the firm.

Lawyers acting for Hunter, Scotland's richest man, claim the executives, who include Tesco's director of corporate and legal affairs Lucy Neville-Rolfe, are trying to force him to give up his shares by launching an unjustified and extravagant refinancing plan to raise £150m.

Hunter asked the court of session in Edinburgh to grant him an interim interdict (an injunction) to block the proposed rights issue before Dobbies' annual general meeting on May 21, to allow time to mount a detailed legal challenge.

Lawyers for Dobbies and Tesco counter-claim that Hunter's allegations are a ploy to put pressure on Tesco to buy out his 29.5% shareholding, while allowing him to gain access to Dobbies' internal plans to expand its business into the Midlands. Hunter's investment company, West Coast Capital (WCC), has a significant share in garden centre company Wyevale.

Richard Keen QC, for Hunter, told Lord Glennie that although Dobbies claimed the £150m was needed to buy sites and take over garden centres, Tesco wanted to use £105m of the funds to pay off its own loans to Dobbies. "It's a movement of cash from one pocket to another," he said. Only £43m would be set aside to expand the business, but that would be placed in a deposit account since the expansion plans were very sketchy, he alleged.

The rights issue would force WCC into spending £44m to maintain its share in Dobbies or see its holding shrink to 15%, leaving Tesco holding well over 75%. That would allow it to delist Dobbies from the Alternative Investment Market (AIM) and in effect run it as a subsidiary of Tesco.

He said Hunter had substantial suspicions about the motives of Neville-Rolfe, the chairwoman of Dobbies, and Tesco's other two non-executive directors on its board, Jonathan Lloyd, the company secretary for Tesco, and Eamonn O'Hare, Tesco's UK finance director.

Keen's allegations were rejected by David Sellar QC, for Dobbies, and Gordon Reid QC, for Tesco. Sellar said: "It's a very serious imputation as to the conduct of the Tesco directors, all of whom are people of some eminence, but also of the two executive directors. At worst it's deliberate misconduct or at best bad faith; these inferences taken together simply don't stack up."

Sellar said that contrary to WCC claims, Dobbies was involved in talks to buy two other businesses, in deals worth £65m. Reid added: "It seems to me that this whole case arises from a commercial strategy and the attempts to show improper purpose on the part of Dobbies' directors is without any firm physical or legal basis."